A high-tech bra fitting machine has been developed so women get the right size bras.
A survey by Marks & Spencer's found 90% wear the wrong size bra.
They have launched the new device to make sure women get the right size cups.
The bra sensor is being launched into 300 M&S stores nationwide.
It takes four measurements and tests the pressure the bra applies to the skin.
The machine is the brainchild of Ian Scott, technology chief for M&S lingerie.
He said, "The sensor doesn't replace the tape measure, but it is a very accurate back-up."
The average British bust measures up to 36C but the most popular bra size is still 34B.